Electric switch



April 24, 1945- H. A. NICKELL 2,374,615

. ELECTRIC SWITCH Filed July 17, 1943 Inventor":

l-li Attorne s.

Her'sheH A. Nickell,

Patented Apr. 24, 1945 ELECTRIC swrrcn I-Iershell. A. Nickell, Schenectady, N. Y'., assignor to General Electric Company, acorporation of New York Application July 17, 1943, Serial No. 495,139

' (o1. 1ss-1 2 Claims.

My invention relates to electric switches, more particularly to shock responsive latches for electric switches, and has for its object a simple, reliable and inexpensive device of this character.

In carrying. out my invention in one form I provide an unbalanced pivoted member provided with a plurality of latch teeth arranged to engage and secure a movable part of the switch or its: operating mechanism. This pivoted member is normally held by a spring in a disengaged posi- .tion and is provided with a weight or inertia member secured rigidly to the member and extending therefrom in a direction at right angles with the pivot of the member so as to be affected by shocks applied to the support for the switch, whereby the latch member is moved by a shock against the tension of its biasing spring into a position to engage and secure the movable part of the,switch.

For a more complete understanding of my invention, reference should be had to the accompanying drawing, Fig. 1 of which is a front elevation. view of an electromagnetically operated switch embodying my invention; Fig. 2 is a side elevation view of Fig. 1; While Fig. 3 is a fragmentary'view showing a latching member in its latching or holding position.

Referring to the drawing, I have shown my invention in one form as applied to the latching of an armature l operated by a load responsive current coil II' and normally biased about its pivot l2 by a helical compression spring l3 to its unattracted position shown in Figs. 1 and 2. The armature I0 is balanced about its pivot 12 by means of a counterweight I3. It carries an adjustable operating screw [4 on its movable end, the lower endof which when thearmature is moved to its attracted position engages and depresses a projection l5 on a latch member I6 made. of a suitably electrically insulating material, such as a molded compound, and mounted on a pivot I I. This latch member I6 is biased clockwise about its pivot I! by a helical compression spring 18 to thevposition shown in the drawing in which a projection IS on its upper end lies over and thereby holds one end of an armature 2B and a bridging contact 2| carried thereby.

which extends a supporting stud 25, the lower end of which is secured to a block of electrically insulating: material 2 0, the block being secured to the upper side of the armature 20. Mounted on the stud 25 is a helical compression spring 16; the lower end of which bearson the bridging 'contact member 2| In the latched attracted position of the armature 2i! shown, the bridging member isheld by th spring 26 with its two arms 21 and 28 in engagement with stationary connection and contact posts 29 and 39 thereby closing a circuit: through itself between these two contact posts.

In accordance with my invention, I provide an unbalanced shock responsive inertia latch arm 3| for latching and securing the armature ID in it unattracted position in th event of a shock applied to the supporting panelmember 32' for the various parts. This latch arm is mounted on a stationary pivot 33 and is biased by a spring 34 in a clockwise direction about the pivot to the position shown in which the armature I0 is free to move to its attracted position. Carried by the armature I0 i a projection 35 provided with a knife edge 36 which is engaged by some one of a series of teeth 31 on the edge of the latch arm 3| adjacent the knife edge 36 so that, when the latch arm is moved counterclockwise about its pivot, some one of the teeth 31 engages the knife edge 36 and secures the armature Ill. 1

For movement of the latch arm in response to shocks, I provide an inertia body 38 consisting The armature 20 is mounted at its other end on a of anarm having one end rigidly secured to the latch arm 3| at an intermediate point thereof by a riveted and Welded joint 39. This member 38 extends substantially parallel with the armature Ill and the supporting panel 32 and laterally with respect to the latch arm 3| in a direction at right angles with the pivot 33. Its lower end, as seen in Fig. 2, is normally held by the spring 33 in engagement with an adjustable stop screw 40. Thus the inertia arm 38 statically unbalances the latch arm 3| about the pivot 33 of the latch arm. In the operation of the device the bridging contact member H is moved to its closed circuit position shown by energization of the coil 24 which pulls the armature 20 to its attracted position where it is latched by the latching projection IS. The coil 24 is then deenergized. Its circuit may be controlled for example by means of a normally open push button switch, not shown. When the coil II is energized sufliciently to move its armature to its attracted position, the screw 14 engages the projection 15 and moves the latch member l6 counterclockwise to release the armature 20- and thereby effect movement of the bridging member 2| to its open circuit position.

It will be understood that, in the event of a shock applied to the supporting panel 32, the counterbalanced armature ID will tend to be -moved toward its attracted -position either directly by the shock or by a component of the shock wherebythe latch member |6 would be moved to disengage the armature 20 and release the bridging contact for movement to its open circuit position. The shock, however, has the same efiect but to a more pronounced extent in producing movement of the unbalanced inertia member 38, which extends substantially parallel with the armature l0, and thereby moves the latch arm 3| counterclockwise about its pivot to a latching position, as shown in Fig. 3, in which one of the teeth 31 has engaged the knife edge 36 and holds the armature H1 in its unattracted position against the effect of the shock. I contemplate that the armature Ill may be moved part way toward its attracted position before it is'latchedby the arm 3|. Suflicient clearance, however, is provided between, the end of the screw H and the projection l to provide for this movementof the armature ID; This clearance can be adjusted by suitable adjustment of the screw. Also, the spring 34 is much weaker than the spring l3 and, therefore, applies a much smaller biasing force to the latch arm 3| than is applied by the spring l3 to the armature III. Consequently, the latch arm is very sensitive to shocks andmoves in response to a shock more quickly than the armature so that some one of the teeth 31 engages and holds the armature before the armature has moved far enough to release the switch operating armature 20.

Icontemplate that the load responsive current coil II will be connected in circuit with a device to be protected, such as an electric motor, so that in the event of a predetermined overload on the motor, the coil is energized sufficiently to attract the armature I0 and thereby effect movement of the bridging member 2| to its open circuit position whereby the circuit of the motor is opened. It will be understood that the bridging member 2| is connected by means of the connection posts 29 and 30 in the circuit of the motor in series with the coil ll. While the armature I0 is balanced by the weight l3 v about its pivot support i2 and is furthermore biased to its unattracted position by means of the spring l3, the armature is nevertheless sensitive to shocks applied to the supporting panel 32. The armature is rendered more sensitive to shocks by reason of the fact that an appreciable amount ofunagnetic attractive force is applied to the armature by the load current in th coil during normal operating load conditions in I the circuit.

operating member mounted on said support of a knife-edge latching projection carried by said member, an arm extending substantially in the direction of movement of said switch operating member having one end mounted on a stationary :pivot and provided with a plurality of teeth at its other end in position to engage said knife- .edge projection, a spring for normally biasing said arm to a disengaged position With respect to said knife-edge projection, an inertia member secured to said arm and projecting laterally from one side of said arm, and a stop engaging said inertia member thereby to limit the position of said arm in response to the bias of said spring, said inertia member unbalancing said arm about its pivot to cause said arm tomove in response to a shockapplied to said support into an engaging latching :position with said knife-edge.

projection.

2.-The combination with a switching device provided with a support and a pivotally mounted switch operating member mounted on saidsupport, a knife-edge latching projection carried by said member, an arm mounted on a stationary pivot and extending substantiallyin the direction of movement of said knife-edge projection,

a plurality of teeth on saidarm in position to engage said knife-edge projection, means nor mally biasing said arm to a disengaged position with respect to said knife-edge projection, an inertia member secured at one end to said arm extending laterally with respect to said armin a direction substantially parallel with said operating member, an adjustable stop engaging said inertia member thereby to limit the position of said arm in response to said biasing means, said inertia member unbalancing said arm about its pivot to cause said arm to move in response to a shock applied to said support to bring one of said teeth into latching engagement with said knife-edge projection before said operating member has moved far enough to carry out a switching operation thereby to secure said operating cmember against movement in a switch operating direction; v

' HERSHELL A. NICKELL. 

